In many power transmission systems, such as gear train systems, continued lubrication is essential to proper operation. The lubrication system must provide a continual supply of lubricant to the moving surfaces, such as the meshing gears, and must perform a cooling effect.
Conventionally, the lubricant is scavenged from the housing or gear box of the power transmission system or gear train and recirculated through a sump to appropriate recirculating pump means. The recirculation circuit may or may not include a filter and the cooling lubricant is returned to the gear box to provide a continuous supply of a cooling medium.
In order to scavenge the lubricant from the gear box, separate scavenge pumps often are employed. In simple power transmissions or gear train systems, separate scavenge pumps have proven quite adequate. However, in more complicated power transmission systems, multiple scavenge pumps must be used to adequately perform the cooling function. When simplicity and weight are important design factors, multiple scavenge pumps have proven either inadequate or undesirable.
For instance, multiple load path transmissions have long been favored for any of a variety of reasons. A typical one of such transmissions includes a rotary input element and a rotary output element. Typically, two or more, substantially identical, gear trains individually connect the input element and the output element. Therefore, the energy or power being transmitted from the input to the output is nominally divided by the number of gear trains interconnecting the two.
Typical advantages flowing from such a construction include the ability to use gears of a lesser face width than would otherwise be required, the use of smaller bearings, the use of lesser material with commensurate weight reduction, and the like. In addition, multiple path transmissions frequently are less noisy during operation than single path transmissions. An example of the use of such multiple load path power transmissions is disclosed herein in conjunction with a turbine for a torpedo or the like.
However, the advantages that may be obtained through the use of a multiple load path transmission are not unaccompanied by disadvantages. One such disadvantage is the circuitous surface areas of such a transmission system which must be continuously lubricated for proper operation. Scavenging the lubricant from such a system, such as the gear box of a multiple load path transmission, can become complicated. Where the multiple load path transmission is used primarily or in part for weight reduction reasons, multiple scavenging pumps defeats the very design parameters for using such a transmission system in the first place. Further problems with such transmission systems are caused in applications where the apparatus itself may attain various attitudes.
This invention is directed to solving one or more of the above problems by providing a unique self-scavenging lubrication system which totally eliminates the necessity of multiple scavenging pumps or other such scavenging apparatus.